MINING HOISTS
Performance of hybrid ropes installed on the Koepe production shaft hoist at a German salt mine versus conventional ropes
by the rope standards applicable in each respective country . Within these regulations , the maximum depth is limited where the shaft hoisting system is still economically viable . The Factor Of Safety ( FOS ) for a system is based in all regulations on the rope properties of the steel components . The wire tensile and the metallic cross section of a rope are leading to the
Minimum Aggregate Breaking Force ( MABF ) and combined with the spin loss factor to the Minimum Breaking Force ( MBF ).”
If a rope is not damaged mechanically , the bending , the tension ratio , and the torsion will eventually lead to the discard of the rope . “ The replacement of a natural or synthetic fibre core in six strand ropes with a high-strength fibre core represents a further development of hoisting ropes within the framework of the applicable standards . The special fibre core is as flexible , does not lead to increased bending stiffness and adds to the rope strength , which reduces the tension ratio during operation . With similar elastic properties in longitudinal elongation as the laid steel strands , a functional bond between strands and core is created - the hybrid rope .”
With the use of a hybrid rope , the tension ratio is reduced , which leads directly to an increase of hoisting cycles for a set of ropes . Load is carried by the core during loading and accelerating , and the wire work in a lower tension ratio is relieved .
A set of hybrid Bekaert ropes was installed on the production shaft on a German salt mine . The shaft is equipped with 4-40 mm ropes on a head mounted Koepe machine . The two former sets 11 and 12 , after the acceleration was increased to 1 m / s ², were discarded after a hoisted volume of 5.8 x 106 t and 6.2 x 106 t with an amount of 130 broken wires over the set reaching the discard criteria . The hybrid set was installed July 2019 and hoisted within five years > 10.2 x 106 t with an amount of seven broken wires in February 2024 . A MRT inspection is done on a half year basis .
Schultheis : “ Hybrid ropes allow the core the take the load , offering low elongation . The ropes were shortened after installation once after two years during the regular two-year change of the rope attachments . The combination of steel with high modular fibres will extend the lifetime of the ropes in a given application and will be the base for further new projects to gain a higher depth with a high hoisting capacity .”
AUGUST 2024 | International Mining 85